Richard V. Baratta, Ph.D., P.E. The Subro Grapevine

 Basics of tissue biomechanics  Basics of injury causation  Injury biomechanics  Situations & their injury potential  Reading medical reports regarding injuries  Warning! Graphic images...

 Anterior: Forward  Posterior: Rear  Medial: Towards the middle  Lateral: Towards the side  Proximal: Close to the head  Distal: Further from the head

 Bone  Ligament  Tendon  Muscle  Other soft tissues

 Hard, mineralized tissue  Cortical – outside, hard  Medullary – inside, “spongy”

 Stronger along the lines where forces are naturally applied

 If you read “spiral fracture”  Think torsion  If you read “transverse fracture”  Think bending  If you read “oblique fracture”  Think axial force  If you read “comminuted”  Think high energy/velocity

 Tough rope-like connective tissue between 2 bones

 Can tear in the middle (midsubstance tear)  Partial or complete

 Can pull off from a bone (avulsion)

 Contractile  Made up of sliding fibers  Create greatest force when forcefully stretched while contracting

 Most tears happen when contracts but is still being lengthened  Most tears happen at the junction between muscle and tendon

 Connect muscle to bone  Structure similar to ligaments

 Can tear  Partial or complete

 Can tear  Partial or complete  Can avulse  Takes great force to tear or avulse normal tendon  Happens when its muscle lengthens against a contraction

 Soft tissues surrounding joints  Thinner than ligaments  Contain joint fluid within the joint  Tear with dislocations

 Muscle  Strain  Tear  Rupture  Most often, muscle tears occur at junction between muscle and tendon  Ligament  Sprain  Partial Tear  Complete Tear  Joint Dislocation

 Skeletal System Anatomy  Upper Extremity  Lower Extremity  Spine  Head

 Radius, Ulna, Carpal bones  Ligaments  Tendons  Carpal Tunnel

 Carpal Tunnel Syndrome “cumulative trauma disorder”  Sprains  Fractures -

 Tennis Elbow (overuse)  Golfer’s Elbow (overuse)

 Fractures  Medial Ligaments

 Ball and Socket joint  Head of Humerus (ball)  Glenoid (socket)  Scapula  Acromion  Clavicle

 P-A force on shoulder or humerus

 Head of humerus comes forward (anterior) out of the socket

 Fairly uncommon (5%)  A-P force on shoulder or humerus  Seizures  Electrocution

 Downwards force on shoulder  Separates clavicle and rest of shoulder  Falls

 Muscles that rotate the upper arm  Injuries are to the tendons, not muscle fibers  Overuse or violent humerus external rotation  Depends on position (abduction)

 Femur, Tibia, Patella  Anterior and Posterior Cruciate Ligaments  Medial and Lateral Colateral Ligaments  Meniscus

 ACL prevents the tibia from moving forward on the femur and from rotating inwards  Cutting  Hyperextension

 Can be injured when a force tries bend the knee in a lateral direction  The ligament getting stretched is the one that gets injured

 Segment Curvatures  Segment Mobilities  Vertebral Body Sizes  Atlanto-Axial Joint

 Viscoelastic (like silly putty)  On high speed impacts, vertebral fractures are more likely than disc ruptures!  The only way to “pop a disc” on a single event is combined compression and bending (torsion helps)

 Injury pattern depends on mechanics  Danger of injuring spinal cord

 High Speed auto accidents  Often fatal  “Raccoon eyes” when not fatal

 Concussion – No structural damage, but some temporary loss of function  Contusion – More serious, bruising of the brain

 Subdural hematoma  Subarachnoid hemorrhage

 Direct impacts to the skull may injure brain on the same side, opposite side, or both sides of where the force is applied

 One of the most highly stressed joints in the body  Direct impact to the jaw or joint  TMJ syndrome – chronic!

 Mechanism of injury  Direct Contact  Exceeding range of motion  Indirect forces  Acceleration (brain injuries)  Loads sustained by tissue  Tissue tolerance to loads  Pre existing conditions (tissue attenuation)

I. Assessment of Situation Mechanics Witness statements Site inspection (regulations, standards, laws) Other information (police reports) Modeling II. Review of Medical Records Determination of claimed injuries Pre-existing conditions III. Analysis Correlation between claimed injuries and event mechanics Differentiate acute and chronic conditions Assess effect of pre-existing conditions

 Arrange in understandable terms  Oral report  Written report  Letter report  Formal report  Litigation support: Posters, demonstrative evidence, video animation  Coordination with attorney  Testimony

True? False?

 “Airbag blew up and flung my arm back and out”  “Bus hit a pothole and steering wheel jerked left” √ X

 “Fell back onto my outstretched hand”  “In the accident (sideswipe)” X √

 “Years of heavy labor”  “In the accident (low speed rear end collision)” X √  Dx: Lumbar disc herniation with osteophytes

 “In the accident (low speed rear end collision)”  “Airbag blew up and hit me in the jaw” X √

 26 y/o woman sustained fatal slip and fall injury in bathroom  Cause of death: brain hemorrhage due to head hitting toilet rim  Reported injuries: 2 scalp lacerations, contusion on right side of neck, anterior iliac spines  Non-reported injuries (evident photographically)  Abrasions on left side of neck (3), chin, both shoulders  Cut lip  2 parallel linear marks on back  Accidental slip and fall? X